1. Field of the Invention
This invention relates to synthetic alkali metal aluminum silicates, and more particularly to sodium aluminum silicate materials useful as fillers and extenders in plastic materials.
2. Related Art
Inorganic fillers and extenders are widely used in the plastics industry to reduce costs and to improve properties of filled plastic compounds. Fillers and extenders can be broadly classified into two major categories--the natural, mined materials and the synthetic products.
Natural fillers/extenders are mined and after further processing and modification are used in the plastics industry. Typical fillers/extenders such as clays, limestone, mica, natural silica, quartz, talc, etc. are included in the category of natural, mined products.
Synthetic fillers and extenders are prepared by chemical reactions conducted under controlled conditions to produce products of desired particle size and end use properties. Typical examples of synthetic fillers/extenders are alumina trihydrate, precipitated calcium carbonate, synthetic calcium silicate, synthetic magnesium silicate, synthetic silica, etc. Synthetic fillers/extenders are generally more expensive than their natural counterparts.
Synthetic alkali metal aluminum silicate materials have also been prepared. For example, U.S. Pat. No. 4,249,903 discloses a process for the preparation of cation-exchanging aluminum-silicate granules useful in the removal of cations which cause hard water during washing of textiles or dishes. Granules having a particle size of about 0.05 to 1 mm are prepared by mixing a finely divided, crystalline water-containing alkali metal aluminum silicate powder with a specified number of moles of SiO.sub.2 in an aqueous alkali metal silicate solution and a specified number of moles of Al.sub.2 O.sub.3 as an acidic hydrolyzing aluminum salt, and mixing until the moisture is uniformly absorbed and a granulate with the specified particle size is formed. The granulate is then dried at a temperature of about 80.degree. to 150.degree. C.
The prior art is also aware that materials have been incorporated into unsaturated polyester compositions. For example, in U.S. Pat. No. 4,081,496, organophilic clay gellant compositions have been incorporated into polyester resins to provide a thixotropic product. In addition, in U.S. Pat. No. 4,008,294, ultra fine polypropylene fibers in epoxy resin compositions have been used to cause the resin compositions to have thixotropic characteristics.
Zeolite molecular sieves were incorporated into polysulfide compositions to increase storage stability of the compositions, as taught by U.S. Pat. No. 3,402,151. Similarly, in U.S. Pat. No. 3,419,533 it is disclosed that fillers and plasticizers such as carbon black, precipitated silicic acid, silicic acid sols, clay, and the like may be incorporated into polyurethane plastics as fillers and plasticizers. Additionally, U.S. Pat. No. 3,607,822 incorporates colloidal silica into polyurethane compositions.
Synthetic sodium aluminum silicate (SSAS) products have previously been used as fillers and extenders in paper, paint and natural and synthetic rubber applications; as carriers and free flowing agents in foods, liquids and chemicals; and as raw material intermediates in many specialty applications. The use of SSAS products as pigment/colorant extenders and as reinforcing fillers in plastics has not been known in the art.